Level of disrespect

I bought earphones for R20 and they worked for 1week, i returned them and was given another pair only for them to do the same thing. I went for a refund this time around and a cashier/supervisor by the name of Phumzile as per her name badge who did the over ride who was at the next till helped the cashier that I was assisted by says "what did you expect for R20 and rolls her eyes and says give her her R20 just like that. Ive never been so disrespected. Why do them sell them then in the 1st place. There are NO manners and manner of approach and was asked if you bought them in May why are you only bringing them now in June?